The present invention involves methods of using particulates coated with a tackifying agent that need not be used immediately once they are prepared and that provide increased viscosity when placed into an aqueous fluid.
Subterranean operations may often use particulates coated with tackifying agents. One example of a production stimulation operation using coated particulates is hydraulic fracturing, wherein a formation may be treated to increase its permeability by hydraulically fracturing the formation to create or enhance one or more cracks or “fractures.” In most cases, hydraulic fracturing involves pumping a particulate-free, viscous fluid (known as a pad fluid) into a subterranean formation faster than the fluid can escape into the formation so that the pressure applied to the formation increases, and the formation breaks, creating an artificial fracture or enlarging a natural fracture. Then a proppant particulate may be added to a fluid to form a slurry that is pumped into the fracture to prevent the fracture form closing when the pumping pressure is released. Often, the proppant particulate may be coated with a tackifying agent to enhance agglomeration and to prevent migration of the proppant particulates after they are placed in the fracture.
An example of a well completion operation using coated particulates may be gravel packing. Gravel packing treatments may be used, among other things, to reduce the migration of unconsolidated formation particulates into a well bore. In gravel packing operations, particles known in the art as gravel may be carried to a well bore by a hydrocarbon or aqueous carrier fluid. That is, the particulates may be suspended in a carrier fluid, which may be viscosified, and the carrier fluid may be pumped into a well bore in which the gravel pack is to be placed. The carrier fluid may leak off into the subterranean zone and/or return to the surface while the particulates are left in the zone. The resultant gravel pack may act as a filter to separate formation sands from produced fluids while permitting the produced fluids to flow into the well bore. A portion of the gravel may be coated with tackifying agent, among other things, to further help control the migration of formation fines. Typically, gravel pack operations involve placing a gravel pack screen in the well bore and packing the surrounding annulus between the screen and the well bore with gravel designed to prevent the passage of formation sands through the pack. Such gravel packs may be used to stabilize the formation while causing minimal impairment to well productivity.
A portion of the particulates used in any type of subterranean treatment may be coated with a tackifying agent, among other things, to control fines migration. It may be useful to precoat the particulates with a tackifying agent prior to reaching the well site to prevent premature consolidation of the particles.